The overall objective of this work is to describe in detail the structure-function of bacterial neuraminidases. The immediate goal is to continue our efforts to characterize the physical and chemical properties of homogeneous neuraminidase obtained from Arthrobacter sialophilus. The mechanism of action of this enzyme will be investigated by studying the interaction of transition-state analogs with the enzyme and by specific and novel site-directing irreversible inhibitors. The latter compounds may also have potential chemotherapeutic value in the treatment of such infectious diseases as influenza and bacterial pneumonia. A radioimmunoassay for A. sialophilus neuraminidase has been developed and will be used to investigate the comparative biochemistry of neuraminidase.